 Photo: courtesy of Ho-kwang Mao and W. A. Bassett A Dented Diamond! (Mao H.-K and Bell, P.M., 1978) |
and Other Strange Moves See diamonds in their natural state here. John Koivula once wrote encouraging me to watch under the microscope what happens when you squeeze a diamond with tweezers while holding it between crossed polars (there is a picture of this in his book, The MicroWorld of Diamonds, page 23). I didn't have a diamond to experiment with, but I've been learning of a more extreme method: diamond anvils<. With these, one can really squeeze a diamond (and everything else) and amazing things happen! Used for research in high pressure studies, one can learn much about the nature of diamonds which goes far beyond what is traditionally considered in gemology. This knowledge then expands those previous notions, opening a fascinating world intrinsically linked to the "4 Cs." | ||
Video: courtesy of W. A. Bassett and Kenji Mibe A short movie taken through one of the two diamonds in a diamond anvil cell. | |||
| The starting material is sandine feldspar and distilled water. As the temperature rises, the sandine reacts with the water and corundum crystals form; though the central crystal is easiest to watch, there are several visible on edge. As it cools, the fluid separates into melt and aqueous solution. The movie starts just at the point it is being reheated. The two fluids homogenize and as this proceeds, the corundum crystals become more visible. The feldspar is a potassium aluminum silicate which provides the aluminium and oxygen for the growth of the corundum; the water provides the mobility for the ions. This illustrates that corundum can have a hydrothermal origin. The pressure changes only slightly with temperature (the temperatures shown are those of the two diamonds). | |||
Meet a Chameleon!  Photo: courtesy of Thomas Hainschwang. The image above shows a 1.01 marquise cut chameleon diamond at room temperature and at 150 degrees C. The yellow is also the color of the diamond when it is in the dark. The color change to green occurs over about 20 seconds when it is brought out into the light. Putting it back into the dark (or heating the diamond, as seen above) will cause it to go back to its yellow groundstate. A favorite book in my library which fueled my fascination with this amazing phenomenon is called "A Green Diamond," published in 1995 by Emmanuel Fritsch, James Shigley, Thomas Moses and George Rossman with Benjamin Zucker and Ian Balfour. It is devoted to the heart-shaped 22 ct Green Diamond - an in-depth study of just that one magnificent chameleon and it sets the stage for the following papers (below). As an educator, one of the best parts is the final chapter which is a narrative of the research ....going behind the scenes of what was a very complicated, but magnificently orchestrated study of this enigma. For more in-depth information and other publications by Thomas Hainschwang, see references at bottom of this page and The GemLab. | |||
 Photo: E. Skalwold A chameleon diamond out from its dark lair. | |||
| In collaboration with photographer Jeff Scovil, with his arsenal of fancy equipment, we finally had success capturing the color change in a chameleon diamond. Our contribution was a metal cap to fit over it. He imaged its fully excited green state on a Friday; Monday morning we entered the studio in complete darkness (on tip-toes for no apparent reason), whipped off the metal cap, and instantly KA-Whoosh! (sound of 5,150 K strobe light going off) - a yellow diamond with just a barest hint of green and a similar result as that obtained by Thomas in the pair of images shown above. | |||
When flawless isn't really flawless...anisotropy in diamond. manifested by differing strengths of birefringence and oriented on octahedral planes. (viewed under crossed polars). Photo: E. Skalwold | |||
 (viewed under crossed polars). Photo: E. Skalwold |
 Birefringence patterns around an inclusion in diamond. (viewed under crossed polars). Photo: E. Skalwold | ||
| Who got me into this but my co-worker and friend, Dr. William Bassett. A Cornell University professor emeritus of geological sciences and Roebling Medalist; Bill is featured here as he ponders the minerals in the cases adjacent to the Bassett Brother's (as I call it) gem collection. Bill is one of the pioneers of diamond anvil cell high pressure research and is the author of many published scientific papers in major journals. Gemologists will also recall the many papers written by Bill's brother Allen on gems and mining in Tanzania and Nepal. Joining his brother, now Bill brings his wealth of knowledge of mineralogy, crystallography and geological processes deep within the earth to illuminate many areas of this sister-science, gemology. | |||
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